Dolby Atmos Beyond 7.1.4 – Part 1

A little over a year ago, I began experimenting with ways to expand my Dolby Atmos surround sound system to beyond the 7.1.4 limitation of current consumer hardware. My continued quest to achieve the best Atmos experience at home has recently driven me to make additional upgrades. These days, my home theater is so crazily complicated that I actually need to run three A/V receivers simultaneously to manage all my speakers.

In most home theaters, 7.1.4 channels of sound should be plenty enough. Even though the Atmos format (as well as its competitor, DTS:X) can support additional speakers, there hasn’t been much demand for that from consumers or much push from manufacturers to do it. Currently, only boutique high-end products such as the $37,000 Trinnov Altitude 32 will decode more than 11 channels at once.

Nonetheless, for some of us, a limit of four height channels isn’t enough to fill the top of the room with sound. My own home theater is a long room with a lot of space behind my seats. That, combined with a low ceiling, makes it difficult for just four speakers (two in the front of the room and two in the back) to image a sound above my head convincingly. This issue is compounded by the fact that the locations where I had installed speakers when I built the home theater (before immersive audio was a concern I gave any thought to) were less than ideal for Atmos. Those speakers are now fixed in place with wiring through the walls and ceiling, and I can’t move them without remodeling the room. That simply isn’t an option.

The better solution is to install additional speakers in the center between the other height channels (Top Middle position). Unfortunately, the asking price for that Trinnov processor is absurdly beyond my budget. I needed to find a way to jury-rig a similar effect for a fraction of the cost.

The First Attempt

I wrote an article last year explaining how I had cobbled together a convoluted system (jokingly dubbed “Zatmos”) utilizing a second A/V receiver to derive extra channels on my ceiling. I advise reading that piece to understand the basic concept of how such a thing is possible.

Even at the time, I was not the only person experimenting with this, and I knew that my Zatmos system was not as ideal as I would have liked it. Over at AVSForum, a member named Scott Simonian had gone even further to use a total of three A/V receivers in unison to create a 7.1.6 configuration (affectionately known as “Scatmos”) more accurate to the intentions of the original Dolby Atmos sound mixers.

For a while, I decided not to go that far. The complexity of installing, connecting and configuring three A/V receivers seemed like overkill to me. I felt that the results I had with Zatmos were good enough to get me most of the way there, and I had a certain amount of egotistical pride that I’d figured out a way to do it with just one extra receiver rather than two.

However, in recent months, my attitude changed and I grew less satisfied with the Zatmos configuration. Eventually, I knew that if I was going to do this, I needed to do it right.

Going Full Scatmos

The silly Zatmos and Scatmos nicknames can be more formally grouped under the heading of “Dolby Atmos Extended.” I want to be clear here that I did not develop the Scatmos process. Credit for that goes to Scott Simonian and others at AVSForum who helped him work it out. With his permission, I’m just trying to explain it here.

For as perhaps ridiculously complicated as they may be to install, one of the saving graces of these experiments is that they can be assembled relatively inexpensively. Although your primary A/V receiver must be a Dolby Atmos (or DTS:X) model capable of decoding 7.1.4 channels of sound from a Blu-ray or UHD immersive audio soundtrack, the secondary receivers don’t need to be nearly as fancy. Any receiver that has, at a minimum, Dolby ProLogic II processing will do. (If using multiple secondary receivers, I recommend that they be identical to each other.)

With a little patience while monitoring For Sale ads on my local Craigslist, I managed to pick up a pair of used Marantz SR4400s for well below $100 each. This is a no-frills, entry-level (or close to it) Dolby Digital/DTS model from 2003. It’s so basic that it doesn’t even have an on-screen menu system. I have to set it up using only the front panel display. The receiver doesn’t have HDMI and cannot handle lossless Dolby TrueHD or DTS-HD Master Audio signals, but it doesn’t need to. All it needs is a pair of analog stereo inputs (which any receiver will have) and ProLogic II.

The simple act of finding a place to put another A/V receiver in my system proved to be far more of an ordeal than I wanted. Because I didn’t have enough space for it on my main equipment shelf, I had to remove all my components, take the shelf apart, rearrange the levels, put most of the equipment back, and hook it up again. Then I had to do the same thing with the second shelf in order to add a level. My Blu-ray and HD DVD players, which had previously been on the main shelf, moved over to the second so that I could keep all the audio equipment together where the speaker wire will reach it. This, in itself, was a tremendous pain to do.

With that finished, here’s the basic idea behind Scatmos: You want to mount six ceiling speakers – in the Top Front, Top Middle and Top Rear positions. (The following sketch does not represent my personal speaker layout, but I’ve drawn it this way to show how it should be done.) Your primary A/V receiver will be set to decode its maximum of 7.1.4 channels, configured as Top Front and Top Rear.

All four of the height channels should be routed to the analog pre-out connections on the primary AVR. You should not attach any speaker wire to those channels on the primary AVR. For all of the height channels, speaker wire will be attached only to the secondary AVRs.

The pre-outs for the Top Front Left and Top Rear Left channels will go into the Right and Left stereo inputs on AVR 2.

The pre-outs for the Top Front Right and Top Rear Right channels will go into the Left and Right (reversed from AVR 2) stereo inputs on AVR 3.

If that sounds confusing already, trying to keep it straight while actually connecting the cables and wires can be truly daunting. I strongly recommend drawing a chart that shows what should go where.

When working properly, each of the secondary downstream AVRs should take a stereo signal consisting of part Front and part Rear, and matrix a Middle channel between them using any mono information in common to both (much as ProLogic II would extract a center channel for dialogue in the front of your room between your left and right speakers under normal circumstances). Thus you get six channels of height information from an original four.

That’s the theory, simplified to its most basic elements. Actually getting it to work properly after your connections are made has some added levels of difficulty that I’ll cover soon in Part 2.

About Josh Zyber

Josh Zyber is a veteran movie and video disc reviewer from Laserdisc to DVD and beyond. He's previously written for DVDFile.com, DVDTalk.com and Home Theater magazine. These days, he wastes most of his free time managing this blog and writing the occasional Blu-ray review for High-Def Digest.

Ross

Josh, what Audyssey Curve do you use in your room? I have always used flat but since upgrading from a Denon X3000 to Marantz SR7009 I have been enjoying the Reference curve especially when using the Atmos decode. It just sounds warmer and fuller. Just curious on what you use.

Audyssey will be covered in the next part of the article. I generally use the Flat curve because I find that Reference rolls off too much high frequency info and I don’t like the sound in my room. However, as it turns out, Audyssey plays havoc with the Scatmos process. (Apparently, it did with Zatmos as well, but I didn’t realize just how much.)

William Henley

Ross

Interesting. Audyssey & Atmos in my room sounds incredible. However, I also did not like the sound of Audyssey Reference in my room with my old X3000. I felt it lacked detail but I also found the Flat curve too harsh which is why I upgraded to the Marantz with XT32. I have Paradigm Monitors which are a little forward so the Marantz tames them quite nicely.

Ronald Moody

Scott Simonian

Volume is controlled from the main AVR only. It’s rather easy when following this same method. You set the levels and everything during setup of the two extra receivers. Once you have everything dialed in, you no longer have to control anything on the two extra receivers and simply control everything on the main AVR. Set and forget.

Just don’t forget to turn on ALL the receivers when watching stuff. 😛 “Hey! how come things don’t sound right. Where is all the overhead stuff? Oh….*facepalm*

This makes sense. My first 7.1 only had 5.1 powered. I ran it into an old amp I had. Once it was set, you didn’t have to mess with the volume on the second amp again, you just controlled the volume on the main receiver.

Both of the secondary AVRs should be set for reference level (0 dB) and left there. You’re using them like amps, just with the addition of ProLogic II. Volume is controlled by the primary AVR. When you raise or lower the volume on that receiver, it changes the signal sent through the pre-outs.

Once, more than 10 years ago, I was researching LaserDisc (because I wanted to buy a used player). I found Josh’s site (years before The Bonus View). Afterwards, I wanted to visit the site again, but couldn’t find it via Google. Then I found out why: I had been using the search term ‘ZyberDISCO’.

In all these variations, did you ever experiment with how well a true, straight 7.1.2 (with the actual overheads) works in your room? It might work so well in my situation because my overheads are about 7-8 feet above the listener position, if they were normal ceiling height they might be far too easy to localize, but my set-up allows for fantastic phantom imaging between the height and lower speakers. I don’t really feel like I’m missing anything. For me it’d either be .2 or .6, .4 (unless you can do a true top-height plus top front or rear–not always an option) seems akin to having a left and right center channel speaker instead of one right in the middle.

Also, I’ve always been a fan of Scott’s design (and Scott himself–one of the best AVS users there is), but I would have reservations about throwing low-grade receiver circuitry into the mix. For once I finally have a receiver and amplifier combo that is dead silent when I crank up the volume (i.e. no hiss) and sound quality is otherwise crystal-clear. Don’t know if I ever asked Scott, but did you notice any changes in sound quality going to your .6 set-up?

Juan

The sad thing is, that is how I thought Atmos was supposed to work (I think DTS X does that) – you pretty much put your speakers wherever, and have as many as you want, and then you used like a 3D mic and it would self configure. so if you wanted that extra side channel (long rooms) or extra rear center, you could get it.

Actually, I bet you probably could do an extra rear center. Take the rear two channels (especially if you have an amp that doesn’t power the rear – so like an older 7.1), then run it into a secondary amp that has prologic and a front center. Then use the front channels on your secondary amp to run your rear left, right and center. Should work pretty well

DTS:X works the same way Atmos does. You have to select from a pre-defined list of speaker locations in the receiver setup menus. The DTS:X marketing hype about “Put your speakers wherever, we’ll figure it out” was a lot of bull.

Scott Simonian

No you don’t. Center rear is wildly inferior to stereo rear surrounds. A center rear directly behind will cause “image reversal”. What that is is when a sound is played (usually briefly like most effects) the sound appears to image in front of you at the front center channel when in fact it’s playing behind you. A little trick our brain does. Have you tried 6.1 surround before? This is very common and no go at all.

Auro3D has support for a center height channel. That’s not a terrible idea but unneeded in the vast majority of domestic applications.

Scott Simonian

Csm101

Question here. I couldn’t find the right place to post it, so I guess here’s good enough. I did some rewiring on my theater rack because my VCR DVD burner crapped out so I figured I’d clean house. I have two Bluray players, one is an older Sony from about 2009 with only one hdmi output. The other is a 3D Panny with two hdmi outputs because I have a legacy receiver that doesn’t have 3d pass through, so in order to get lossless and 3d, I needed a player with both. I like having two players so I can do picture comparisons whenever a newly remastered bluray comes out, so I decided if I wanted to compare audio tracks as well and more efficiently,( i.e., pcm track on an older disc vs DTS track on newer disc) I would wire the old Sony through the receiver, which then goes to the TV, but that means in order to watch anything in that player, I always have to turn my receiver on. I don’t have to do that with my Panny because of the dual outputs. The question is, is there a setting on the receiver or the bluray player that will allow the signal to pass through without having to power it on? I’m aware the equipment is a little older and if it can’t be done, then that’s ok, but I’d figure I’d give it a try. Thanks in advance to anyone with input on this.

Eric

hey guys liking all this conversation im a little confused even though ive read the atmos manual for engineers -the mixer has 10 channels and 10 only .i realize that we can set up 34 channels but from what ive studied it sounds like say the front heights and wide fronts are the same channel information as the ear level fronts and again the front tops and rear tops are the exact same two channel stereo or mono only not at all truly four channels the atmos mixer only has 10 or 9.1 channels count them out! theres not enough to get four top speakers 7.1 .2 thats two distinct stereo channels in the top set up, in the Manual they just call it good old fashion 9.1 no fancy 11.1.4 i guess with some sort of delays the objects and metadata pan to all the other 24 channels? yes

I’m not sure what manual that is or what any of that means, but an Atmos soundtrack does have discrete audio to all speakers. The Dolby Atmos demo disc has an audio test where a helicopter circles the room from Top Front-Left to Top Rear-Left, then over to Top Rear-Right and Top Front-Right.

I think perhaps you’re confusing the difference between “bed channels” and “sound objects.” An Atmos soundtrack is built on a base of 7.1 bed channels, just like a traditional soundtrack. The mixer decides what speaker he wants a sound to come from, and he puts it in that specific speaker. On top of that, Atmos adds sound objects that are not tied to specific speakers. Sound objects move through the three-dimensional space in the room, and the decoder maps them to whatever speaker is closest to their intended location.

Eric

hey Josh thanks for posting all your findings very interesting and thoroughly done job but wait it doesn’t help me lol because it seems at the moment a 7.1,4 or an 11 channel amp costs minimally what $3000 and im not buying in at that price so in a couple days im getting the Sony str dn1080 5.2.2 for $600 call me cheap or stupid but i want that receiver for a lot of other reasons also including the price so Josh ive been trying to figure out how im going to fake it(7.1.4) till i make it lol- (make serious dough that is ) because theres no poor boy 7.1.4 receiver yet. so can you start over with a 5,1,2 system and teach us how to do one of them up lol ? im sure your saying hells NO! thanks 🙂 remember your the Boss! of Atmos youve created Zacmos lol u kin do it!!!!! so do us poor boys a favor and design a set up for us

Unfortunately, there’s no way to expand a 5.1.2 receiver to more channels. You’d need to start with a receiver that can decode at least 5.1.4.

I don’t know where you’re located, but a 7.1.4 receiver shouldn’t cost you $3,000. If you’re in the U.S., accessories4less.com currently has a Marantz SR6011 for $949.99. This receiver has 9 channels of built-in amplification, but can decode 11 channels (7.1.4) if you add an external amp, which should only cost a little over $100. Yes, this is more than the $600 you’re planning to spend now, but it’s nowhere near $3,000.

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